Method and apparatus for precision squeeze tube valving, pumping and dispensing of work fluid (s)

Abstract

Presented is a method and apparatus for precision control of work fluids in a squeezable tube that has no surge of work material during the shut off closing of the tube which is accomplished by a compensator moving simultaneously and oppositely to the shut off member movement, each of the compensator and the shut off member having different stroke lengths and tube engageable surface areas which effectively keep the internal volume of the tube the same. The method and apparatus are useful standing alone, in coordination with precision positive displacement pumping under computer control which is also presented, and as a part of sequential or simultaneous movement of a valve/pump dispensing head coordinated with a stationary or movable work piece to provide exceedingly fine control dispensing. Suckback between dispensing shots is coordinated with shut off and movements of inlet, outlet and dispensing members to afford operator programmable dispensing with precision and without drip.

I claim: 
     
       1. Valve means for on/off flow permitting/preventing of flowable work material in a squeezable tube means comprising: a) a first member means operable to move toward and away from said squeezable tube means to cause constriction and relief of constriction in said squeezable tube means, said first member having a first length of stroke and having a first tube engagement area means of predetermined size;   b) a second member means operable to move toward and away from said squeezable tube means to cause constriction and relief of constriction of said squeezable tube means, said second member means having a second length of stroke, and having a second tube engagement area means of second predetermined size, said second member means being characterized as having said second length of stroke being less than said first length of stroke, and said second area means predetermined size is greater than said first area means predetermined size;   c) connection means for causing said first member means and said second member means to move in substantially opposing simultaneous directional relationship; whereby the flow of flowable work material in said tube means is substantially unaffected by movement of said first member.     
     
     
       2. The valve means set forth in claim 1 wherein said movement of said first member means is reciprocal linear movement in a plane substantially transverse to the axis of said tube means. 
     
     
       3. The valve means set forth in claim 1 wherein said connection means further comprises pivotal mechanical linkage means, said pivotal mechanical linkage means assuring substantially simultaneous opposite directional movement of said first member means and second member means whereby when said first member means is causing a constriction in said squeezable tube means, said second member means is relieving a constriction in said squeezable tube means, the amount of constriction and relief of constriction being substantially equal. 
     
     
       4. The valve means of claim 3 further comprising adjustment means, said adjustment means being associated with said second member means and being operable to adjust the furthest constriction position of said second member means relative to said squeezable tube means and the said second length of stroke. 
     
     
       5. The valve means of Claim 4 wherein said second length of stroke has a short adjustable portion and said furthest constriction position is located and arranged relative to the full constrictive position of said first member means such that said short adjustable portion of the second length of stroke causes further relief of constriction of said tube means after said first member means is in its full constrictive position whereby a back pressure is created adjacent said second movable member to provide suck back of flowable material. 
     
     
       6. The valve means of claim 1 wherein said first member means and second member means are located in relatively close proximity to each other.